Automatic nuclear-magnetic-resonance positioning apparatus

ABSTRACT

Nuclear-magnetic-resonance positioning apparatus for automatically calibrating a reference line on a recording paper with a specimen to be analyzed containing a standard substance. The apparatus includes means for detecting the distance between the resonance center line of the standard substance and the reference line of the recording paper and providing a DC magnetic field corresponding to this distance as a bias for the swept DC magnetic field utilized in the spectral analysis of the specimen. Namely, a wiper of a potentiometer is mechanically rotated to an angle corresponding to the distance and a bias signal of the potentiometer is applied to the coil which applies the magnetic field to the specimen.

United States Patent [1 1 Utsumi et a1.

1111 3,774,102 [451' Nov. 20, 1973 AUTOMATIC NUCLEAR-MAGNETlC-RESONANCEPOSITIONING APPARATUS Inventors: Yoshiharu Utsumi, 1182, lchige;

Noriyuki Matsubayashi, 1030, lchige, both of Katsuta, Japan Filed: Dec.29, 1971 Appl. No.: 213,460

Foreign Application Priority Data Dec. 29, 1970 Japan 45/128536 US. Cl324/05 R Int. Cl. G0ln 27/78 Field of Search 324/05 R, 0.5 A,

324/05 AC, 0.5 AH, 0.5 MA

References Cited UNITED STATES PATENTS 12/1963 Parker 324/0.5 R

OSC

3,137,813 6/1964 Kroon 324/05 R Primary Examiner-Michael .1. LynchAttorney-Craig, Antonelli & Hill [57] ABSTRACTNuclear-magnetic-resonance positioning apparatus for automaticallycalibrating a reference line on a recording paper with a specimen to beanalyzed containing a standard substance. The apparatus includes meansfor detecting the distance between the resonance center line of thestandard substance and the reference line of the recording paper andproviding a DC magnetic field corresponding to this distance as a biasfor the swept DC magnetic field utilized in the spectral analysis of thespecimen. Namely, a wiper of a potentiometer is mechanically rotated toan angle corresponding to the distance and a bias signal of thepotentiometer is applied to the coil which applies the magnetic field tothe specimen.

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Y ATTORNEYS AUTOMATIC NUCLEAR-MAGNETIC-RESONANCE POSITIONING APPARATUSThe present invention relates to an apparatus for the automaticpositioning or calibration of a reference line on a recording paper innuclear magnetic resonance apparatus.

In hydrogenous nuclear magnetic resonance of high resolution, thespacing between the resonant line of a l0 standard substanceincorporated as an internal standard and a measuredresonant line isindicated by the rate (ppm) of change in a swept DC magnetic field,which rate is termed the chemical shift. For hydrogenous nuclearresonance, tetramethylsilane is generally used as the standard substancefor comparison purposes.

When nuclear-magnetic-resonance spectra are recorded on recording paperby applying a highfrequency magnetic field of a fixed frequency and aswept DC magnetic field to a specimen to be measured with the standardsubstance incorporated thereto, the resonant line of the standardsubstance does not always appear at the position of an identical DCmagnetic field, but is generally slightly deviated in position. This isbecause the volume susceptibilities of the respective specimensincluding specimen tubes differ from one another, and hence, truemagnetic fields to which atomic nuclei in the specimens are subjectedvary slightly. In this case, it is very convenient for the spectroscopicanalysis if the recording is made with the resonant line of the standardsubstance being brought into coincidence with the reference line on thespectra recording paper. This is called the calibration chart system.

The calibration chart system, or the positioning operation for bringingthe position of the resonant line of the standard substance intocoincidence with the reference line on the recording paper, hasheretofore been carried out by a manual and time consuming operation.

It is therefore an object of the present invention to provide anuclear-magnetic-resonance apparatus which eliminates the need formanual positioning or calibration.

It is another object of the present invention to pro-- vide anuclear-magnetic-resonance apparatus which automatically performs thepositioning or calibration of the .apparatus for spectral recording.

In accordance with an embodiment of the present invention, the automaticnuclear-magnetic-resonance apparatus includes recording paper having apredetermined reference line thereon and in order to make the resonancecenter line of the standard substance coincide with the predeterminedreference line position on the paper, means are provided for detectingthe distance between the resonance center line and the reference line onthe recording paper in the form of a voltage corresponding to thedistance. A wiper of a potentiometer is rotated mechanically togetherwith the recording of the resonance center line and the angular positionof the wiper corresponds to the distance and the current supplyprovides, as a bias, a current corresponding to an output of thepotentiometer in a coil which applies the magnetic field to a specimen.

These and further objects, features and advantages of the presentinvention will become more obvious from the following description whentaken in connection with the accompanying drawing which shows forpurposes of illustration only, one embodiment in accordance with thepresent invention, and wherein:

FIG. 1 is a somewhat schematic view of the present invention;

FIG. 2 is an enlarged view of the recording means of FIG. I; and

FIG. 3 is a graph illustrating the operation of the separator of FIG. 1;

Referring now to the drawing, there is shown in FIG.

l, a high-frequency oscillator l of a fixed frequency, e.g. 60 MHz, bymeans of which a high-frequency magnetic field is applied to a specimen2 which is placed in a DC magnetic field of, for example, 14, I00 gaussgenerated by a magnet. When the strength of the DC magnetic field isswept in such a way that a DC current fed to the magnet coil 12 isvaried, signals induced by the resonance of hydrogenous nuclei in thespecimen are supplied via an amplifier 3 and are recorded as spectra onrecording paper 4 of a recorder.

In the recording operation, a pen 5 of the recorder is swept toward theright in the drawing with the sweep being controlled by a motor 6, whichis coupled via coupling strings to pulleys 7, 8 and 9. The pulley 9 isconnected to a rotor of a potentiometer 10. A voltage produced in thepotentiometer 10 supplies a DC current to the magnet coil 12 via amagnet control circuit 11. In this manner, the sweep or variation of thestrength of the DC magnetic field and the pen 5 of the recorder areinterlocked with each other.

In the prior art arrangements having manual operation of theabove-described system, the calibration is carried out by manuallyadjusting a potentiometer 15 so that a resonant line 13 of a standardsubstance coincides with a reference line 14 on the recording paper.Thus, the strength of the swept DC magnetic field is manually adjustedfor every specimen. More specifically, if the specimen is exchanged, theposition of the resonant line 13 is slightly shifted due to variationsin specimen tubes and the like. Therefore, at each exchange, thepotentiometer 15 is adjusted to perform the desired positioning orcalibration.

In accordance with the present invention, the positioning operation isnot carried out by adjustment of the potentiometer 15, but isautomatically effected by apparatus including a lamp 16 which provides alight for irradiating a mark in the form of a slit 17 provided at aspecified position on the recording paper. When the light passes throughthe slit and falls upon a photosensitive element 18 disposed on the penrider 5, a signal is generated. As shown in FIG. 1, the apparatus alsoincludes a separator 19 for separating resonance dispersion componentsof the spectral signal and a clutch controller 20 which is actuated by asignal from the separator 19. More specifically, when the separator 19determines that the swept magnetic field has passed through the centerline of the resonance signal, an output signal is provided for actuatingthe clutch controller 20 which operates a clutch 21 which isselfmaintained in the operative condition. The clutch 21 serves forconnecting a potentiometer 22 to the pulley 9 such that with rotation ofthe pulley in accordance.

with the sweep, a wiper of the potentiometer 22 is rotated, and a DCvoltage is generated in the wiper. When the photosensitive element 18passes overthe light slit 17, a relay 23 is energized by the outputsignal from the photosensitive element 18 and the relay selfmaintainedin the energized condition. Simultaneously therewith, the clutch controlcircuit 20 is actuated by the output signal from element 18 fordisengaging the clutch 21. As a result, a DC voltage proportional to therevolutional angle of the wiper of the potentiometer 22 is stored in thepotentiometer. The stored voltage value is applied to the magnet controlcircuit 11 via the relay 23 such that the magnet coil 12 has a DC biascurrent added thereto which serves for shifting the spectral position.

The apparatus of the present invention also includes a relay 25 forapplying to the magnet control circuit 11 a DC magnetic-field changevoltage which corresponds to the spacing between a reference line 14 onthe recording paper and the slit 17. When the photosensitive element 18is located to the left of the light slit 17, the relay 25 is in theclosed state and is self-maintained in this condition. Simultaneouslywith the passage of the photosensitiveelement over the light slit 17,the relay 25 is opened and changes the swept DC magnetic field.

The operation of the automatic calibration apparatus will now bedescribed in more detail with reference to FIG. 2. As shown in thisfigure, a resonant line 26 corresponds to a preparatory measurementbefore the spectral recording and upon detection of the resonant line,the clutch 21 is energized via the separator 19 and clutch control 20.The relay 25 is in the closed state and the potentiometer wiper 22 ofFIG. 1 starts rotation at the central position 27 of the resonant lineand when the photosensitive element 18 passes through the position ofthe light slit 17, the clutch 21 is disengaged and the rotation of thewiper 22 is stopped. In this case, a magnetic field bias voltageequivalent to II as shown at 28 is obtained as the revolutional angle ofthe wiper 22. The term AI-I shown at 29 in the drawing represents amoving width of the recording paper as caused by the DC magnetic fieldstrength change due to the opening and closure of the relay 25 in FIG.1, and is made the voltage equivalent of'the spacing between thereference line 14 on the recording paper and the light slit 17. In thismanner the bias voltage to be applied is obtained in a preliminarycalibration measurement. Thus, the spectral recording is started from apoint at which the photosensitive element 18 has passed through thelight slit 17 and is carried out by sweeping the pen rider 5 to theright. During the spectral recording, the clutch 21 is in the disengagedstate, the relay 23 is in the closed state, and the relay 25 is in theopen state. Consequently, the resonance center line 13 of the standardsubstance and the reference line 14 of the recording paper alwayscoincide at the end of the spectral recording.

FIG. 3 is a diagram for explaining the manner in which the resonancecenter line may be determined by the separator 19. The dispersioncomponents of the resonant line have a shape as at 30 in this figure.Accordingly, the resonance center position may be discriminated suchthat when a DC component of the dispersion mode of the resonance signalexceeds a predetermined level 31 on the positive side at point A andsubsequently arrives at the zero level at point B, an output signal isgenerated by the separator. An electric circuit for carrying out suchdiscrimination may be constituted by utilizing two voltage comparatorsand a gate circuit.

It can be seen that in accordance with the present invention, thepositioning or calibration operation for bringing the resonant line of astandard substance into 5 coincidence with the reference line of spectrarecording paper is automatically effected whereby the disadvantages ofthe manual and time consuming procedures utilized especially inspectroscopic analysis are overcome.

It should be noted that while in the aforedescribed embodiment, thedescription has been directed to the method of effecting the sweep withthe high-frequency magnetic field kept at a fixed frequency and with thestrength of the DC magnetic field being varied, the method of varyingthe frequency of the high-frequency magnetic field is also utilized inthe principle of the nuclear magnetic resonance and may be achieved withthe present apparatus. In addition, while the measurement and storage ofthe quantity of correction and H in FIG. 2 are made in the presentembodiment by the combined use of the potentiometer wiper 22 and theclutch 21, the measurement and storage may also be accomplished withother electrical means such as an electrical integrator.

Obviously, many modifications and variations of the present inventionare possible in the light of the above teachings. It should therefore beunderstood that within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described.

We claim:

1. In an apparatus for recording nuclear-magneticresonance spectralsignals wherein a specimen to be analyzed has a standard substanceincorporated therein, an automatic nuclear-magnetic-resonancepositioning apparatus comprising recording means having a recordingmedium for recording the spectrum of the nuclear-magnetic-resonance,writing means for writing the spectrum on the medium, and driving meansfor moving said writing means, said recording medium having marksthereon, means for applying a predetermined frequency signal to saidspecimen, magnetic sweeping means for applying a DC magnetic field tosaid specimen and for varying the DC magnetic field in accordance withthe movement of said writing means, means for shifting the resonanceposition of the standard substance with respect to said marks of saidrecording medium, means for measuring the resonance spectrum of saidspecimen and standard substance and for applying said spectrum to saidrecording means, means for storing a signal value corresponding to thedeviation of the resonance center line of the standard substance fromone of said marks of said recording medium and for applying the signalvalue as a bias during the spectral analysis of the specimen to ensureproper positioning of the spectral response of the specimen on saidrecording medium, first detecting means for detecting the resonance peakof the standard substance and for providing an output signal forcontrolling the operation of said storing means in response thereto, andsecond detecting means for detecting said writing means passing one ofsaid marks of said recording medium and providing an output signal forcontrolling the operation of said shifting means and the application ofthe signal value of said storing means to said magnetic sweeping meansas a bias.

2. Apparatus according to claim 1, wherein said first detecting means isresponsive to a DC component of a dispersion mode of the resonancesignal from said measuring means first exceeding a predetermined signallevel and the subsequent arrival of the component at the zero signallevel for providing the output signal.

3. Apparatus according to claim 1, wherein said recording medium is arecording paper, and'the marks being in the form of a slit in therecording paper and a reference line on the paper.

4. Apparatus according to claim 3, wherein said means for measuring andstoring a deviation signal value includes a potentiometer having arotatable wiper movable in accordance with the writing means of saidrecording means, the movement of the wiper being started in response tothe output of said first detecting means and being stopped in responseto the output of said second detecting means, the rotational angle ofthe wiper corresponding to the deviation of the resonance center linefrom one of the marks of the recording paper.

5. Apparatus according to claim 1, wherein said recording medium is arecording paper having a first mark in the form of a slit and a secondmark corresponding to a reference line spaced a predetermined distancetherefrom corresponding to the sweep width for achieving resonance ofthe standard substance.

6. Apparatus according to claim 5, wherein said first detecting meansincludes means responsive to a DC component of a dispersion mode of theresonance signal first exceeding a predetermined signal level and thesubsequent arrival of the component of the zero signal level forproviding an output signal.

7. Apparatus according to claim 6, wherein said mag netic sweeping meansincludes magnetic coil means, first potentiometer means having a wiperarranged for movement with said driving means of said recording meansfor providing a varying signal to said magnetic coil means, and saidstoring means includes second potentiometer means having a wiper, andclutch control means responsive to the output of said first detectingmeans for activating a clutch for engaging the wiper of said secondpotentiometer means for movement with said writing means, said clutchcontrol means being responsive to the output of said second detectingmeans for deactivating said clutch.

8. Apparatus according to claim 7, wherein said second detecting meansincludes light means for irradiating said slit in said recording paperand photosensitive means carried by said writing means and positionedfor movement over said slit, said photosensitive means being responsiveto the irradiation of said slit when said writing means passes thereoverfor providing an output signal.

1. In an apparatus for recording nuclear-magnetic-resonance spectralsignals wherein a specimen to be analyzed has a standard substanceincorporated therein, an automatic nuclear-magneticresonance positioningapparatus comprising recording means having a recording medium forrecording the spectrum of the nuclearmagnetic-resonance, writing meansfor writing the spectrum on the medium, and driving means for movingsaid writing means, said recording medium having marks thereon, meansfor applying a predetermined frequency signal to said specimen, magneticsweeping means for applying a DC magnetic field to said specimen and forvarying the DC magnetic field in accordance with the movement of saidwriting means, means for shifting the resonance position of the standardsubstance with respect to said marks of said recording medium, means formeasuring the resonance spectrum of said specimen and standard substanceand for applying said spectrum to said recording means, means forstoring a signal value corresponding to the deviation of the resonancecenter line of the standard substance from one of said marks of saidrecording medium and for applying the signal value as a bias during thespectral analysis of the specimen to ensure proper positioning of thespectral response of the specimen on said recording medium, firstdetecting means for detecting the resonance peak of the standardsubstance and for providing an output signal for controlling theoperation of said storing means in response thereto, and seconddetecting means for detecting said writing means passing one of saidmarks of said recording medium and providing an output signal forcontrolling the operation of said shifting means and the application ofthe signal value of said storing means to said magnetic sweeping meansas a bias.
 2. Apparatus according to claim 1, wherein said firstdetecting means is responsive to a DC component of a dispersion mode ofthe resonance signal from said measuring means first exceeding apredetermined signal level and the subsequent arrival of the componentat the zero signal level for providing the output signal.
 3. Apparatusaccording to claim 1, wherein said recording medium is a recordingpaper, and the marks being in the form of a slit in the recording paperand a reference line on the paper.
 4. Apparatus according to claim 3,wherein said means for measuring and storing a deviation signal valueincludes a potentiometer having a rotatable wiper movable in accordancewith the writing means of said recording means, the movement of thewiper being started in response to the output of said first detectingmeans and being stopped in response to the output of said seconddetecting means, the rotational angle of the wiper corresponding to thedeviation of the resonance center line from one of the marks of therecording paper.
 5. Apparatus according to claim 1, wherein saidrecording medium is a recording paper having a first mark in the form ofa slit and a second mark corresponding to a reference line spaced apredetermined distance therefrom corresponding to the sweep width forachieving resonance of the standard substance.
 6. Apparatus according toclaim 5, wherein said first detecting means includes means responsive toa DC component of a dispersion mode of the resonance signal firstexceeding a predetermined signal level and the subsequent arrival of thecomponent of the zero signal level for providing an output signal. 7.Apparatus according to claim 6, wherein said magnetic sweeping meansincludes magnetic coil means, first potentiometer means having a wiperarranged for movement with said driving means of said recording meansfor providing a varying signal to said magnetic coil means, and saidstoring means includes second potentiometer means having a wiper, andclutch control means responsive to the output of said first detectingmeans for activating a clutch for engaging the wiper of said secondpotentiometer means for movement with said writing means, said clutchcontrol means being responsive to the output of said second detectingmeans for deactivating said clutch.
 8. Apparatus according to claim 7,wherein said second detecting means includes light means for irradiatingsaid slit in said recording paper and photosensitive means carried bysaid writing means and positioned for movement over said slit, saidphotosensitive means being responsive to the irradiation of said slitwhen said writing means passes thereover for providing an output signal.